Method and apparatus for treating pulp



Oct. 13, 1931. H NA AN 1,827,280

METHOD AND APPARATUS FOR TREATING PULP Filed Dec. 24, 1929 P 1 V 1 W T Fly-Z ""l IIIIIHIIB IIIIII I g ./3 i

lllllllll 'lllllllll I i I i i i Patented Oct. 13, 1931 UNITED STATES PATENT oFFics GEORGE HOLMES OMAHA-N, OI HEWYYOBK, H. Y, ABSIGHOBTO RUBBER SURI'ACEBS, 1N0. OF WILMINGTON, DELAWARE, A CORPORATION OF DELAWARE METHOD AND AP PARATUS FOR TREATING PULP Application flled'necember 24, 1929. mm in. 410,254.

This invention relates to an improved method and apparatus for treating fibrous material and more articularly for beating pulp or pa en stoc whereby the felting properties 0 the fibers are improved and,in the case of vegetable fibers, the fiber substance is also hydrated while minimizing the shortening of the fiber length which results from the cut-ting or breaking of the fibers when beaten by the methods now commonly used. The new method and apparatus also reduces the time usually re uired for the beating treatment and pro uces a stock which improves the tearing, tensile, bursting and folding strength of the paper made from it. It has been the practice in metallurgical and allied arts to utilize a machine, generalor stamp-mill, for the 1y known as a stam crushing and pulverization of ores andothe r material which it is desired to crush. The essentials of a stamp are a heavy weight, means for liftin the weight and a mortar in which the weig t is allowed to fall. The material to be treated is placed in the mortar and is crushed by the impact of the falling weight. The stamp-mill ordinarily used has a mortar and a number of stamps arranged in a row and means for raising them at'irregular intervals so that they strike the mortar at difierent instants. The mortars are usually made in'the form of cast iron boxes. The impact of. the stamp is received by a die, a cylinder of chilled cast iron, which rests in the mortar. The stamp itself comprises a stem which carries a tappet for lifting the stamp and the boss or head which supplies the weight to the stamp and the shoe which makes the contact with the die when the stam falls. The stamps are'lifted' by means 0 cams which are mounted on a cam shaft. The cam shaft runs the length of the-stam mill and the cams are mounted on it, accor ing to the order of the drop of the stamps desired. The material tobe treated is usually fed into the stamp mill at one side and withdrawn from the other. In the early days of the paper industry a mill similar to the present ordinary stamp mill was utilized in the treatment of rags. This stamping also cause the fibers to cut each other.

cast iron dies and shoes of the ordinary ma-' chine however, are not suitable for treating pulp because of their hard and rigid nature. The dies and'shoes of the ordinary stamp-mill ordinarily do not wear evenly and with a relatively soft material such as wood pulp containin a relatively large portion of water, the e ective contact between the dies and the shoes would be limited to a relatively small pro ortion of the, face of the shoe. Because 0 this small area of con-- tact the efi'ect of the impact on the fibers of wood pulp or paper stock would be to shear or cut the fibers so that the fibers, to

a large extent, would be cut off, with the result that the fibers so cut would not only be shortened but would be left with more or less clean ends instead of a frayed or torn condition, which is desirable to give a pul good felting properties. The hard unyleld ing impact of the ordinary stamp-mill would With the present invention, such a'cuttin action is largely avoided and the fiber bun les are disintegrated or separated into their individual-fibers by a crushing action substantially devoid of cutting efiects and the individual fibers are given the desired flattened and frayed condition by a non -cutting rubbing and crushing action. This is accomplished by roviding the dies or the stamps, and refera ly both the dies and the stamps,

of t e ordinary stamp-mill with resilient yielding cushion-like surfaces which exert on the pulp a crushing eflect without cutting. The dies of the ordinary mill ma be entirely replaced by a solid bed of this yleldstamping.

ing resilient material running the entire length of the mortar, and the dies of the ordinary stamp-mill may be made entirely of this resilient yielding material. Preferably these dies (or bed) and shoes are of rubber, (by'which I mean to include rubbercovered dies or shoes), the rubber being used being of about the consistencv of that used in rubber automobile tires: The word rubber as used throughout the specification and claims includes not only rubber and rubber compositions in a strict sense, but also rubber substitutes and equivalent compositions having the proper rubber-like consistency and physical characteristics for making yielding resilient surfaces suitable for performing the method of the present invention. These cushion-like surfaces of rubber or equivalent substances not only yield as a whole to the pulp but are also capable of yielding locally to bundles of fiber or bunches, thereby further minimizing danger of injuries to the fibers during the stamping process. In the practice of the present invention the pulp to be treated is ordinarily fed into a stamp-mill at one end and "with drawn at the opposite end, different from the practice when stamping ores. The stamps are raised and allowed to fall in the desired order by means of the rotation of the camshaft and the fibers are subjected to a continuous stamping treatment as they travel through the length of the stamping-mill and are withdrawn. The length of treatment of I the. individual fibers is regulated by regulating the depth of the pulp in the mortar in relation to the rate of feed and withdrawal, i. e., if the depth of pulp is relatively high. as

compared to a relatively low rate of feed and withdrawal, ,the, individual fibers will be subjected to a relatively long period of The fiber bundles and fibers are thus subjected, substantially without cutting them, to a stamping action characterized by rubbing, crushing. flattening, pulling and bruising by the resilient surfaces so that the fiber bundles are sepa gited into their individual fibers and the fibers are hydrated and frayed asv contrasted with the cutting action of the ordinary methods used for beating pulp. The degree of hydration depends largely upon the severity and duration of the stamping process.

The surfaces of the rubber or rubber-covered dies or bed andshoes may be flat or may have convex or concave surfaces of equal or unequal degree'of curvature, i. e. a shoe may.

be provided with a convex rubber surface and the corresponding die or bed may have a flat surface. The shoe may have a convex surface and the corresponding bed or die may'have a concave surface of equal or greater or less degree of curvature, or the shoe may have a concave surface, and the correspon ing bed or die may have a convex surface of equal aeaaaeo or greater or less degree of curvature. in this way the rubbing and kneading effect of the present process can be intensified or accentuated. When the shoe has a concave surface and the corresponding bed a convex surface of less degree a of curvature, there will be a kneading and rubbing effect between the two surfaces as the impact makes them touch each other at all points. The fibers subjected to such action are rubbed and pulled as well as flattened and bruised. The convexity or concavity as discussed above may bes herical, spheroidal, or cylindricaL- Theru ber surfaces of the stamps and bed may also be rough or irregular. They may have a number of ridges across the contact surface, which ridges are compressed or flattened when the impact occurs. In this way the kneading effect may be further intensified.

The stamps may also be provided with rubber surfaces out at an angle from the horizontal of, for exam 1e, 45 to 60, and arranged to fall on ru ber surfaced dies having a similar slope. Either or both stamp and die could be left with the natural flex of the rubber or could be reinforced with a spring for added stiffness. In this way the pulp would be 'rubbedand squeezed between two flat flexible surfaces. The angular slope of the stamp would create less splash or a tetion. A further alternative would inclulfe an inverted V-shaped stamp which would fall on a V-shaped die, or vice versa, either or both of rubber.

"As a result the felting properties of the fibers. are improved and a more uniform close web is obtained when .thepulp passes over the the ordinary heater and the pulp is relatively free from out fiber and blunt ends found in the pulp beaten in an ordinary beater. Paper can be produced from the pulp resulting from the beating process of the present invention having higher tensile strength and bursting strength, higher tearing strength and higher foldin strength than with the same pulp beaten y' usual methods. Moreover, the pulp itself is a free pulp from which the water readily drains away faster than with pulp treated to the same extent in an ordi nary beater. Freeness, as that term is used in paper making, denotes the rate at which v8 which may be p need at the water drains away from the pulp on the wire of the paper making machine. The principal factors affecting freeness are the hydration of the individual fibers and the average length of the fibers. Hydration tends to make a pulp slow (that is, less free), but that is more than offset by the fiber length resulting from the method of the present invention. A free pul is desirable in that it permits increasing the-speed of the paper making process, and hence reduces the cost, for the reason'that the water will drain away faster from the pulp on the wire and the presses will express more water than from a ess free pulp and hence the'volume of the water which must subse uently be removed from the dryers is reduced. By reason of the increased average length of the fibers produced by the new method of the present invention the freeness of the pulp is improved notwithstanding the fibers are adequately hydrated. a

In the accompanying drawings which i llustratethe new a paratus suita 1e for practicing the new met 0d:

Fig. 1 is a sectional elevation of a stampmill suitable for use in the present )rocess;

Fig. 2 is a sectional view showin t 1e mortar, stamp and cam in their or inary arran ement in respect to each other.

e pulp or stock to be treated is fed con-. tinuously to the mortar3 by means of spiral feed 4, and thru the feed 5, or by an other means of maintaining a "constant fee The pulp enters the mortar 3 at 6 and passes through the length of the mortar in a right to left direction and is withdrawn at opening 7. The 'openin 7 is provided with a weir roper height to maintain the desired deptl zi of pulp or stock in the mortar. As the pulp passes through the mortar 3 it is subjected to stamping action between the stamps 9 and the bed or die 10. In the apparatus shown, both the stamps 9 and the bed 10 are provided'with' a surface 11 of rubber. 4 The stamps are lifted by means of cams 12 which operate 0114118; tap ets 13. The cams are mounted on acam sha 14 which is provided wi'h a pipe 15 to which power may .beap lied for turning the cam shaft, and thereby lifting the stamps.

The cams are placed on the cam shaft in such a manner that adjacent stamps do not strike the bed simultaneously. The particular order of drop of the apparatus shown is indicated by the relative position of the stam s at some one instance, as shown in the drawing. The stamps may be of any desired number and may be made to drop in any desired order. With the rubber surfaces of thepresent invention the rebound of each stamp after the impact will be ater than that of the ordinary stamp-mil so that the stamps will not have to be lifted to their height by the action of the cam alone but will be caught at some point above the point of impact and from that point raised to their full height. As the power for running the stamp-mill is consumed by the overcoming of gravity and of friction, the power saved by this decrease in the distance which the stamp must be raised in relation to the length of its drop will materially increase the 'efliciency of the stampmill. The length of drop, of course, is dependent upon the size .Of the cams used, and such length of drop may be regulated by regulating the size of the cams. The impact depends also upon the weight of the stamp as well as the length of drop and this factor can also be varied to give the impact desired. It may be desirable to have stamps of different length of drop in the same stamp-mill and this can also be accomplished by having corresponding cams of different size.

The present invention has to do with the treatment of the fibrous material by a crushing and rubbing action substantially devoid of cutting action, and with the yielding resilient or cushion-like stamping elements performing that function. As illustrated in Figs. 1 and 2, the contact surfaces or shoes of the stamps and the bed of the mortar are made ofsolid rubber. The bed of the mortar may be made in the form of a continuous strip running the full length of the mortar and cemented to the mortar, or it may be made in sections to facilitate replacing parts of the bed when worn without disturbing the I understood, of course. that these difierences exist only in the method of applying the force. and the present invention may be applied to them with equal facility. 7

Although it is' preferable that both the stamps and thebed or dies be supplied with rubber contact surfaces. the advantages of the invention may be realized to a measurable extent, either if one or the other of the stamping elements be equipped with the usual metallic surfaces provided the other is equipped with the yielding resilient surface. and treatment by such yielding-stamping elements'on one side of the pulp only is included in the invention and intended to be secured by the claims, except in those claims which are expressly'limited to such treatment on both sides of the pulp.

In the apparatus Ill all

While the present invention is of particular tial thickness wherebythe impact is modified value for the beating of chemical wood fiber, by the resilient and yielding nature of such rsaaaeo it includes in its broader aspects the beat- Surfaceing of other materials which require similar treatment.

I claim:

1. A stamping machine for fibrous material, comprising a mortar and stamps. one at least of which is provided with yielding resilient stamping elements adapted to beat the fibrous material passing between the mortar and stamps by a crushing and rubbing and kneading action without substantial cutting action.

2. A stamping machine for fibrous mate rial, comprising a mortar and stamps, both of which are provided with yielding resilient stamping elements adapted to beat the fibrous material passing between the mortar and stamps by a crushing, rubbing and kneading action without substantial cutting action.

3. A stamping machine comprising a mortar and stamps. one at least of which is provided with yielding resilient surfaces extending across the path of material passing between the mortar and stamps.

4. A stamping machine comprising a mortar and stamps. one at least of which is provided with rubber stamping elements.

.5. A stamping machine comprising a mortar and stamps, one at least of which is provided with rubber beating surfaces extending across the path of material passing between the mortar and stamps.

6. A stamping machine comprising a mortar and stamps. both of which are provided with rubber beating surfaces extending across thepath ot the material passing between the mortar and stamps.

7. A stamping machine comprising a mortar and stamps provided with cushion-like 7 surfaces of yielding resilient material.

8. A. stamping machine comprising a mortar and stamps both of which are provided with surfaces of yielding resilient material.

9. The method of treating fibrous material, which comprises subjecting such material to regular successive blows in a stamping machine between stamping members, one at least of said members having resilient yieldable surfaces of substantial thichiess, said surfaces being of substantial area and substantially parallel to each other.

10. The process accordingto the preceding claim in which both surfaces are resilient yielding surfaces between which the fibrous material is subjected to the regular successive crushing blows.

ll. The method ofbeating paper pulp, which comprises subjecting a thin layer of such pulp to regular successive blows in a stamping machine between stamping members of substantial area,'one of said members having a yielding resilient surface of substanln testimon whereof I afiix my si ature. GEORG" HOLMES GARN N. 

